05-11-13, 11:21 AM
(05-11-13, 08:24 AM)richfzs link Wrote: Being closer to, or further away from, the sun has got foc all to do with it. The difference, in percentage terms, is tiny.
What is important, is the tilt from the vertical axis. Think on a beam of light, and for arguments sake, every beam of light is a foot wide. When that beam of light is aimed squarely at a surface, it covers an area a foot wide - but if you start to tilt the surface it's hitting, it suddenly covers a bigger area. So the energy it contains is spread thinner, less energy for a given area, hence it's cooler.
When we're tilted towards the sun, we have summer, and vice versa.
In addition, the northern hemisphere is also closer to the sun during 'our' winter.
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